
 Question:
 What is best transformation of Y so that T(Y) vs. X is
most linear?
 Definition:
 Vertical Axis : Correlation coefficient of T(Y) and X
 where T(Y) is the BoxCox transformation
of Y
 Horizontal Axis: BoxCox power transformation parameter
(lambda)
 Interpretation/Conclusion:
 Best transformation is lambda = 0.6. Note that the
square root transformation (lambda = 0.5) is a reasonable
choice in this case.
 NIST/SEMATECH Handbook Chapter:
 1.
Exploratory Data Analysis
 4.
Process Modelling
 References:
 NIST/SEMATECH eHandbook of Statistical Methods,
BoxCox Linearity Plot, 6/2003.
 Box and Cox (1964), "An Analysis of of transformations,"
Journal of the Royal Statistical Society,
Series B 26 (2): 211–252.
